The invention concerns a water table for a thermal-cutting machine, especially for processing aluminum, with an underwater plasma-based cutting system, with a surface that is immersed in a tank of water and that supports the material, and with a device for raising and lowering the level of the water.
Designing a water table of this type entails a number of problems, especially in relation to raising and lowering the level of the water and removing residue from the cutting process.
It has for example been discovered that a lot of gaseous hydrogen occurs, especially when aluminum is being cut with a plasma torch, leading to from slight to serious explosions. This situation is due to the molten aluminum becoming atomized under the water and expelled from the incision by the kinetic energy of the plasma jet. The particles of metal are lifted by steam tension and precipitate in the capacity of cutting residue through the water, with known chemical conditions leading to a reaction that results in aluminum oxide and hydrogen.
The level of the water is raised and lowered in known water tables by means of air traps in the form of cuffed bells or compartments, within which explosive mixtures can accumulate, however, due to the aforesaid formation of hydrogen when aluminum is cut with an underwater plasma torch because particles of the metal can enter when the chambers are flooded.